Construction workers dismantled a crane at the World Trade Center site on Friday.

At the World Trade Center construction site in Lower Manhattan, crews were readying 10 tower cranes for high winds ahead of Hurricane Irene’s arrival.

“We are not concerned about flood risk,” said Chris Ward, executive director of Port Authority of New York and New Jersey, which owns the site. “We are concerned about high winds, as it relates to the tower cranes in particular.”

The cranes, some of which are being used to build 1 World Trade Center, will be either secured with cables or left to swing free depending on their location, Ward said. The tower is now 90 stories high, on its way to becoming the tallest building in New York City.

Letting cranes swing “like a boat on a mooring” sometimes makes damage less likely because it reduces torque that would result from cranes being tied down, Ward said.

Workers are also looking at whether they need to secure trees at the September 11 memorial on the site. That memorial is scheduled to be ready for visitors in two weeks, on the 10th anniversary of the 2001 terrorist attacks.